Type and Severity of Cognitive Decline in Older Adults after Noncardiac Surgery

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Abstract
Background: The authors investigated type and severity of cognitive decline in older adults immediately and 3 months after noncardiac surgery. Changes in instrumental activities of daily living were examined relative to type of cognitive decline. Methods: Of the initial 417 older adults enrolled in the study, 337 surgery patients and 60 controls completed baseline, discharge, and/or 3-month postoperative cognitive and instrumental activities of daily living measures. Reliable change methods were used to examine three types of cognitive decline: memory, executive function, and combined executive function/memory. SD cutoffs were used to grade severity of change as mild, moderate or severe. Results: At discharge, 186 (56%) patients experienced cognitive decline, with an equal distribution in type and severity. At 3 months after surgery, 231 patients (75.1%) experienced no cognitive decline, 42 (13.6%) showed only memory decline, 26 (8.4%) showed only executive function decline, and 9 (2.9%) showed decline in both executive and memory domains. Of those with cognitive decline, 36 (46.8%) had mild, 25 (32.5%) had moderate, and 16 (20.8%) had severe decline. The combined group had more severe impairment. Executive function or combined (memory and executive) deficits involved greater levels of functional (i.e., instrumental activities of daily living) impairment. The combined group was less educated than the unimpaired and memory groups. Conclusion: Postsurgical cognitive presentation varies with time of testing. At 3 months after surgery, more older adults experienced memory decline, but only those with executive or combined cognitive decline had functional limitations. The findings have relevance for patients and caregivers. Future research should examine how perioperative factors influence neuronal systems.